Recent studies have suggested that some psychotic patients have abnormalities of neuromuscular regulation and structural abnormalities of motor neurons and neuromuscular junctions. This plan outlines electrophysiological studies of 1) spinal monosynaptic or H-reflexes in such patients and 2) neuromuscular transmission in muscle biopsy specimens maintained in vitro. Correlations will be sought between the physiological parameters and the structural abnormalities of nerve and muscle, diagnostic and clinical assessments of psychopathology, medication effects, and other patient variables. Finding electrophysiological correlates of clinical psychopathological states would facilitate our assessment and treatment of psychotic patients.